Golf balls

Abstract

A golf ball center composition comprising by weight 100 parts of a resilient elastomer, not more than 25 parts of a monomer capable of grafting, cross-linking or chain-extending the elastomer and not less then 70 parts of an inert filler, the composition being cured and having a Shore C hardness of not less than 60°; a golf ball comprising said center, an elastic thread wound around the center to form a core, and a cover molded onto the core; and a method of making such golf ball.

Having thus described our invention, what we claim and desire to protect by Letters Patent is: 
     
       1. A golf ball comprising a center, an elastic thread wound around the center to form a core, and a cover molded onto the core, the center being formed from a composition comprising: (1) a cis-polybutadiene elastomer having a cis-content of not less than 80%;   (2) not more than 25 parts by weight per hundred parts of elastomer of a monomer capable of grafting, cross-linking or chain extending the elastomer said monomer is selected from the metal salt of an unsaturated carboxylic acid and a polyol ester or anhydride of a polybasic unsaturated carboxylic acid; and   (3) not less than 135 parts by weight per hundred parts of elastomer of an inert filler; said composition being cured and having a Shore C hardness of not less than 60° and being characterized by not requiring freezing of the center in order to wind the elastic thread around the center.   
     
     
       2. A golf ball according to claim 1 in which the Shore C hardness is not less than 70°. 
     
     
       3. A golf ball according to claim 1 in which the elastomer consists wholly of polybutadiene having a cis-content of not less than 96% by weight. 
     
     
       4. A golf ball according to claim 1 in which the monomer is the metal salt of an unsaturated carboxylic acid, the metal ion being uncomplexed and having a valence from 1 to 3. 
     
     
       5. A golf ball according to claim 4 in which the monomer is the reaction product of zinc oxide with methacrylic acid or acrylic acid. 
     
     
       6. A golf ball according to claim 1 in which the monomer is present in from 5 to 20 parts by weight. 
     
     
       7. A golf ball according to claim 1 in which the filler is present in from 135 to 300 parts by weight per 100 parts of elastomer. 
     
     
       8. A golf ball according to claim 1 in which the center composition includes a silane coupling agent. 
     
     
       9. A golf ball center composition comprising by weight 100 parts of a cis-polybutadiene elastomer having a cis-content of not less than 80%, not more than 25 parts of a monomer capable of grafting, cross-linking or chain-extending the elastomer said monomer is selected from the metal salt of an unsaturated carboxylic acid and a polyol ester or anhydride of a polybasic unsaturated carboxylic acid and not less than 135 parts of an inert filler, the composition being cured and having a Shore hardness of not less than 60° and being characterized by not requiring freezing in order to wind an elastomeric thread around the center to form a golf ball core. 
     
     
       10. A composition according to claim 9 in which the inert filler is present at about 135 parts to about 300 parts. 
     
     
       11. A composition according to claim 9 in which the elastomer consists wholly of polybutadiene having a cis-content of not less than 96% by weight. 
     
     
       12. A composition according to claim 9 and including a silane coupling agent. 
     
     
       13. A golf ball center composition comprising by weight 100 parts of a cis-polybutadiene elastomer having a cis-content of not less that 80%, not more than 25 parts of a monomer which is a metal salt of an unsaturated carboxylic acid and which is capable of grafting, cross-linking or chain-extending the elastomer and not less than 135 parts of an inert filler, the composition being cured and having a Shore C hardness of not less than 60° and being characterized by not requiring freezing in order to wind an elastomer thread around the center to form a golf ball core. 
     
     
       14. The composition of claim 9 wherein the monomer is methacrylic acid or the zinc salt thereof. 
     
     
       15. The composition of claim 13 wherein the monomer is methacrylic acid or the zinc salt thereof. 
     
     
       16. The composition of claim 1 wherein the filler is barytes. 
     
     
       17. The composition of claim 9 wherein the filler is barytes. 
     
     
       18. The composition of claim 1 wherein the filler is barytes. 
     
     
       19. The golf ball of claim 1 wherein the elastic thread is a double thread.